I was playing on hardcore 1680x1050 24-36 FPS xD took me like 3 min to make an account.
A couple things I heard that help the logging in issues is don't use the Launcher to start the game. Make sure it's set to run as Admin. You can't create an account through the game, ever! Try online.
Mine worked fine by using my EA account login. It's not very specific on whether it wants your EA account, gamespy account or mycrysis.com account.
Yeah make sure you use the nickname and not your email on the login.
Ya, this is gay.. tried EA, Gamespy, and mycrysis accounts... none of them work... (and yes, crysis is allowed through the firewall)